W220 S Class Suspension Issues Explained(+Most Common Problems)

In this brief article we are going to discuss the different Mercedes W220 S Class Suspension problems including AirMatic issues, what the causes are, and Troubleshooting Tips.

What are the most common suspension issues in a Mercedes W220 S Class? 

The most common Mercedes W220 S Class suspension issues are:

  • Knocking or Creaking Sounds while going over Bumps
  • Vehicle Self-Steer under hard acceleration
  • Suspension Sagging
  • Vehicle would be sitting lowe
  • Squeaking Noises
  • Suspension Error message
  • Rear suspension Riding Lifted

W220 S Class Suspension

The Mercedes-Benz W220 was a sedan model range otherwise also known as the Mercedes-Benz S-Class, succeeding the earlier S-Class W124 generation. The W220 generation of S-Class lasted from 1999 to 2005.

The models under the W 220 were :

S 280, S 320, S 350, S 430, S 500, S 600, S 55 AMG, S 65 AMG, S 320 CDI, S 400 CDI

The basic Suspension set-up would be the same for subsequent generations as well. The W220 Air suspension, also called AIRmatic suspension had the basic set-up of: 

  • Front Independent double wishbone suspension with AIRmatic Strut and an anti-roll bar. The upper Control Arm is a single-wishbone for all vehicles.

The Lower control arm is a combination of 2 ‘Thrust Arms’ with 2 separate ball-joint connections to the knuckle.

  • Rear 5 – link arrangement with an AIRmatic Strut and an anti-roll bar

The AIRmatic was basically meant to be a combination of adaptive damping that adjusts Damping rates continuously based on road inputs and selected driving style alongside air springs resulting in an extremely comfortable ride.

Knocking or Creaking Sounds while going over Bumps

  • The front suspension makes ‘Knock’ or ‘Creak’ sounds every time the vehicle goes over even small-sized bumps on the road
  • Sometimes there is dark brown oil stains on the lower control arms

Troubleshooting Knocking or Creaking Sounds

  • While there are multiple reasons for Knock or Creak sounds, the most susceptible component within the suspension would be the Lower Control Arm or ‘Forward Tension Strut’ Bushing
  • The Bushing has a Rubber Bushing at one end and a Ball joint at the other.
  • The Control arm Bushing is “Hydraulically filled’ Rubber bushing. Generally, this part only lasts about 40K- 50K miles and mostly fails after that mileage. The dark oil stains, if any, are from the Hydraulic Fluid that escaped the bushing after it ruptured owing to wear

Pro-Tip

  • While replacing the Control arm, look for a good aftermarket solution that would give more service life compared to the Rubber-Hydraulic bush.
  • You could either go for a ‘Solid’ Rubber bushing or a Mono-Ball type of Bearing instead of the Rubber-Hydraulic Bush

Vehicle Self-Steer under hard acceleration

On some occasions, when driving spiritedly, you might notice that when you accelerate hard, the vehicle tends to exhibit a sort of “Torque Steer”, or in other words, the vehicle tends to steer without any steering input from the driver.

Troubleshooting Vehicle Self/Torque Steer

  • Since it happens during acceleration in your Rear-wheel drive car, the source of the problem is most probably related to the rear suspension
  • There seems to be Rear-Wheel Toe-Change under acceleration, which makes the vehicle tend to steer.
  • Toe-change is controlled by the Rear suspension Toe-link. Hence, the condition of this link and its joints needs to be checked.

AIRMATIC System Related

Suspension Sagging

  • When parked for a while, one or more corners settles very low in height as compared to the remaining corners.
  • On starting the vehicle, the corner would rise, but only temporarily before sagging again.
  • The car would be at an uneven height even while driving
  • The 2 major reasons behind suspension sag are:
    • Leakage in the Air Strut
    • Ride Height Sensor malfunction

Troubleshooting Corner Sagging: Airmatic Strut Leak

  • The most probable cause would be damage to one or of the AirMatic Struts which led to a leakage and loss of air pressure. 
  • Therefore the particular strut was unable to maintain the required ride height
  • One quick check you could do to verify that it is the Strut, is to press the ‘Axle Lift’ Button and watch how the suspension tries to raise itself.
  • The Front generally goes up first in Axle-Lift. If there is a problem or leak in any one of the front Air Struts, then the suspension will either not be able to fully raise itself, or,

go up slightly and lower itself immediately, while the other corners are raised.

  • In cases where the leakage is major, there will also be a “Hissing’ Noise while doing Axle-Lift due to the Air Leakage

Troubleshooting Corner Sagging: Failed Ride Height Sensor

  • If the Ride Height sensor is broken, damaged or locked, it will cause the AirMatic system to get confused and not maintain ride height

Vehicle sitting low and unable to raise

  • Vehicle would be sitting low generally after being parked for a while.
  • Even when the ignition is turned on, the suspension would not raise itself again
  • In certain cases, there would be no compressor noise
  • In some cases you might get this error message, 

‘AIRMATIC: VISIT WORKSHOP.’ 

The problem could be most likely due to an electrical fault. You should use an OBD II scanner and get it to display all the fault codes. 

Troubleshooting Vehicle sitting Low: Leakages in the Air Lines

  • If the suspension sits low, it mostly means that there is either ‘Low’ or ‘No’ pressure at the Air Struts
  • There is a possibility of leakage at any of the connection points within the Air circuit. 
  • You can easily identify the points of leakage by spraying soap and water all over the entire air circuit lines and then observing for the appearance of bubbles.
  • There is also the probability of leakages at the Air connection fittings in the valve block.
  • For any connector fittings, in case of any leakages, be sure to replace the connector

Troubleshooting Vehicle sitting Low: AirMatic Compressor Failure

  • If you find no compressor working noise, then this would most probably be the cause. 
  • The compressor would stop working in the following situations: 
    • Burn-out of the Compressor
    • Blown fuses and Relays of the compressor
    • leakages in the air lines leading to loss the of minimum pressure required to allow air suspension functioning

Troubleshooting Vehicle sitting Low: Blown fuses and Relays of the compressor

  • It could happen due to either a voltage surge in the circuit or just simply due to age. 
  • Occasionally, a relay or fuse could fail due to loads over longer periods while engaging with the compressor.
  • In a majority of cases, an overworked compressor is usually a sign that there is a leakage or blockage within the Air suspension system

Troubleshooting Vehicle sitting Low: Airmatic Solenoid Valve Block Malfunction

  • The Valve Block has solenoid valves that control the pressure to each corner Air strut.
  • A malfunctioning Valve block solenoid could block air to the air struts

Squeaking Noises

  • In normal driving going over uneven surfaces, the suspension makes ‘squeaking’ and ‘mild rattling’ noises

Troubleshooting Squeaking Noises

  • The Mercedes Airmatic Strut has the Air Spring integrated with a damper/shock absorber inside
  • Like with conventional shock absorbers, if the Airmatic Shock absorber or Damper fails and loses Damping oil, it would lead to internal wear if the piston and subsequent squeaking noises when the vehicle runs.
  • The Airmatic shock absorber could fail due to:
    • A part defect
    • Incorrect assembly of the air strut top and bottom mounts
    • Shock Absorber reaching its end-of-life, which generally between 80K to 100K miles of service

Rear suspension Riding Lifted

  • The Rear suspension is at maximum Ride height at one or both then corners
  • Rear suspension height does not come back to normal until the ignition is turned off.

Troubleshooting Rear suspension Riding Lifted

Two possible Causes for such a symptom:

  • Rear Height Sensor is malfunctioning. If the Ride Height sensor is broken, damaged or locked, it will cause the AirMatic system to get confused and not maintain ride height
  • Rear Height Sensor Calibration was not carried out. This needs to be done using a Mercedes Benz Diagnostic tool. The diagnostic tool has a calibration function that helps level the 4 corner suspensions.

Conclusion

In this brief article we have discussed the different Mercedes W220 S Class Suspension issues including AirMatic issues, what the causes are, and Troubleshooting Tips.

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